LIQUID CRYSTAL DISPLAY DEVICE WITH DYNAMICALLY SWITCHING DRIVING METHOD TO REDUCE POWER CONSUMPTION

• US 20090128540A1
• Filed: 01/25/2008
• Published: 05/21/2009
• Est. Priority Date: 11/20/2007
• Status: Active Grant

• Current Assignee: AU Optronics Corporation
• Original Assignee: AU Optronics Corporation
• Inventors: Hsu, Chao-ching
• Granted Patent: US 8,654,112 B2
• Time in Patent Office: Days
• US Class Current: 345/213
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2330/02 Details of power systems and of start or stop of display operation
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2330/022 in absence of operation, e.g. no data being entered during a predetermined time
• CPC Class Codes: G09G 2330/023 using energy recovery or conservation
• CPC Class Codes: G09G 2340/0435 Change or adaptation of the frame rate of the video stream
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

A liquid crystal display device of reducing power consumption includes a liquid crystal panel having a plurality of liquid crystal capacitors for displaying an image, an input interface for generating a scan control signal, an oscillator for generating a predetermined frequency, a control unit electrically coupled to the oscillator for outputting a current control signal when a frequency of the scan control signal is lower than the predetermined frequency, and a driving circuit electrically coupled to the controller for generating a first bias current to charge the plurality of liquid crystal capacitors of the liquid crystal panel.

Claims

1. A liquid crystal display device having dynamically switching driving modes, comprising:

a liquid crystal panel comprising a plurality of liquid crystal capacitors for displaying an image;

an input interface for generating a scan control signal;

an oscillator for generating a predetermined frequency;

a control unit, electrically coupled to the oscillator, for outputting a first current control signal when a frequency of the scan control signal is lower than the predetermined frequency; and

a driving circuit, electrically coupled to the controller, for generating a first bias current to charge the plurality of liquid crystal capacitors based on the first current control signal.

2. The liquid crystal display device of claim 1, further comprising a timing controller, wherein the control unit and the oscillator are integrated within the timing controller.

3. The liquid crystal display device of claim 1, wherein the control unit comprises a comparator.

4. The liquid crystal display device of claim 1, wherein the driving circuit comprises a source driver.

5. The liquid crystal display device of claim 1, wherein the scan control signal comprises a scan line clock signal (YCLK), and when the frequency is lower than the scan control signal, the driving circuit outputs the first current control signal.

6. The liquid crystal display device of claim 1, wherein the input interface comprises a low voltage differential signaling (LVDS) controller, and the scan control signal comprises a low voltage differential signal.

7. The liquid crystal display device of claim 6, wherein the control unit is used for controlling the driving circuit to generate a second bias current which is greater than the first bias current, when the frequency of the scan control signal is greater than the predetermined frequency.

8. The liquid crystal display device of claim 7, wherein the control unit is used for generating a second current control signal when the frequency of the scan control signal is greater than the predetermined frequency.

9. The liquid crystal display device of claim 8, wherein the driving circuit is further used for enabling charge recycling function in response to the second current control signal.

10. A method of reducing power consumption of a liquid crystal display device, the liquid crystal display device comprising a liquid crystal display panel, the liquid crystal display panel comprising a plurality of liquid crystal capacitors, the method comprising:

selecting a frame rate;

generating a scan control signal based on the frame rate; and

outputting a first bias current or a second bias current to charge the plurality of liquid crystal capacitors of the liquid crystal display panel, based on the scan control signal frequency.

11. The method of claim 10, wherein the scan control signal comprises a low voltage differential signal.

12. A method of reducing power consumption of a liquid crystal display device, the liquid crystal display device comprising a liquid crystal display panel, the liquid crystal display panel comprising a plurality of liquid crystal capacitors, the method comprising:

(a) generating a scan control signal;

(b) providing a predetermined frequency;

(c) outputting a current control signal based on a frequency of the scan control signal and the predetermined frequency; and

(d) outputting a bias current to charge the plurality of liquid crystal capacitors of the liquid crystal display panel, based on the current control signal.

13. The method of claim 12, wherein step (d) comprises:

outputting a first bias current to charge the plurality of liquid crystal capacitors when the frequency of the scan control signal is greater than the predetermined frequency;

outputting a second bias current which is smaller than the first bias current to charge the plurality of liquid crystal capacitors when the frequency of the scan control signal is less than the predetermined frequency.

14. The method of claim 12, further comprising:

(e) enabling a charge-recycling function when the frequency of the scan control signal is less than the predetermined frequency.

15. The method of claim 12, wherein the scan control signal is associated with a frame rate of the liquid crystal display panel.

16. The method of claim 12, wherein the scan control signal comprises a scan line clock signal (YCLK).

17. The method of claim 12, wherein the scan control signal comprises a low voltage differential signal.

18. The method of claim 17, wherein step (c) comprises outputting a current control signal when a frequency of the scan control signal is less than the predetermined frequency.